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Sybase 10.0.2 very slow after OS / Sybase re-install.

2 posts in Windows NT Last posting was on 1997-11-21 07:23:24.0Z
Mike Insch Posted on 1997-11-19 20:28:52.0Z
From: "Mike Insch" <elvis@the.pearly.gates.com>
Subject: Sybase 10.0.2 very slow after OS / Sybase re-install.
Date: Wed, 19 Nov 1997 20:28:52 -0000
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Hi,
Recently, we had to re-install Sybase 10.0.2 on one of our Production
boxes due to a problem with the OS. It was running under NT3.5, SP3 but the
system kept falling over when any high intensity task (such as LOAD
DATABASE) was carried out. We re-installed the OS, it is now NT3.51 SP5,
and restored the data from the old production DB into the new database, and
this seemed to be OK.

The problem is this: The new system seems to be *very* slow when it is
writing data (ie. INSERT, UPDATE, DELETE). It seems to run at about the
same speed as our Development system for SELECT's, but an INSERT which used
to take 4 - 6 seconds on the production system now takes up to 1 minute.
Has anyone else had this problem?

The machine is a dedicated Sybase server, and there are only about 10
users. The machine is an Apricot VXft 1500 (Pentium 90, 32MB). I have
tried starting Sybase with the 'performance' switch ('-P'), but this only
took a couple of seconds off the run time. Trying things like this is also
rather tricky since it is a well distributed system, I am 100 miles from the
server, and the client systems are mostly Long distance ISDN links. We have
ruled out the ISDN as the source of the problem since clients on the Local
network are having the same problem as the more remote users.

The clients are connecting to the server using IPX/SPX from Win3.11
machines. The software they are using is written in PB4.0. The server is
set up to allow connections via named pipes and IPX/SPX. Using TCP/IP is,
unfortunatly, not an option.

The structure of the database has recently been changed to accomodate an
upgrade / extention to the PB software, but none of these changes affected
the old DB structure except to add a couple of Foreign Key references. (In
fact the extention was what highlighted the original problem, prompting the
OS re-install). The database is about 400MB (with 200MB log), and Sybase
has 130MB tempdb. The new database is correctly indexed (according to DBCC
reindex and DBCC checktable), and it will be growing to about 1.5GB to
accomodate new data and users once this problem is fixed.

Apologies for being a bit long winded, but I wanted to give as much info
as possible, since this is becoming a big headache and I need to get it
fixed real soon.

Thanks In Advance,
--- Mike Insch (mike@vofka.demon.co.uk)


Brad Brown Posted on 1997-11-21 07:23:24.0Z
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Subject: Re: Sybase 10.0.2 very slow after OS / Sybase re-install.
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Article PK: 1081486

Mike,

did the logs move from some disk to the same used for data and indexes
during the upgrade?

The only real (physical) writes required to complete modifications are
log entries. The command completes as soon as these log entries are
recorded. My thought is that you may have two hard drives. In the old
setup an independent drive was used for logging; but in the new setup,
the log has been moved to the same disk as data and indexes. Having the
log on an independent disk is much faster (5-10X). This can be checked
by using sp_helpdb, sp_helpdevice to see which physical devices are
used.

Possible second explanation: Sybase attempts to turn off write-cache
for its devices. This may have been defeated in SP3 but enabled in
SP5. I have no way of checking this.

good luck
bb

Mike Insch wrote:

> Hi,
> Recently, we had to re-install Sybase 10.0.2 on one of our
> Production
> boxes due to a problem with the OS. It was running under NT3.5, SP3
> but the
> system kept falling over when any high intensity task (such as LOAD
> DATABASE) was carried out. We re-installed the OS, it is now NT3.51
> SP5,
> and restored the data from the old production DB into the new
> database, and
> this seemed to be OK.
>
> The problem is this: The new system seems to be *very* slow when
> it is
> writing data (ie. INSERT, UPDATE, DELETE). It seems to run at about
> the
> same speed as our Development system for SELECT's, but an INSERT which
> used
> to take 4 - 6 seconds on the production system now takes up to 1
> minute.
> Has anyone else had this problem?
>
> The machine is a dedicated Sybase server, and there are only about
> 10
> users. The machine is an Apricot VXft 1500 (Pentium 90, 32MB). I
> have
> tried starting Sybase with the 'performance' switch ('-P'), but this
> only
> took a couple of seconds off the run time. Trying things like this is
> also
> rather tricky since it is a well distributed system, I am 100 miles
> from the
> server, and the client systems are mostly Long distance ISDN links.
> We have
> ruled out the ISDN as the source of the problem since clients on the
> Local
> network are having the same problem as the more remote users.
>
> The clients are connecting to the server using IPX/SPX from
> Win3.11
> machines. The software they are using is written in PB4.0. The
> server is
> set up to allow connections via named pipes and IPX/SPX. Using TCP/IP
> is,
> unfortunatly, not an option.
>
> The structure of the database has recently been changed to
> accomodate an
> upgrade / extention to the PB software, but none of these changes
> affected
> the old DB structure except to add a couple of Foreign Key
> references. (In
> fact the extention was what highlighted the original problem,
> prompting the
> OS re-install). The database is about 400MB (with 200MB log), and
> Sybase
> has 130MB tempdb. The new database is correctly indexed (according to
> DBCC
> reindex and DBCC checktable), and it will be growing to about 1.5GB to
>
> accomodate new data and users once this problem is fixed.
>
> Apologies for being a bit long winded, but I wanted to give as
> much info
> as possible, since this is becoming a big headache and I need to get
> it
> fixed real soon.
>
> Thanks In Advance,
> --- Mike Insch (mike@vofka.demon.co.uk)